Written By: Rob Willcott Physiotherapist
“We don’t treat anatomy – we treat physiology.” – David Butler
When I first read this quote by David Butler I wasn’t exactly sure what it meant. However, through my own research and experience I gained a greater appreciation for this quote. At one time I used manual therapy (MT) based on a biomechanical model. I would try and feel facets and other joints glide. I believed that I could locate the problematic joint thought to be the source/cause of pain. After many years of trying to convince myself that I could feel these subtle motions I came to the conclusion that you can’t. Thankfully, the literature supported my conclusion.
First of all, the use of motion palpation to determine positional faults has poor reliability (Troyanovich et al., 1998; Seffinger et al., 2004). Of course, I’m sometimes told that I haven’t taken enough courses or treated enough patients to feel these subtle movements. But that’s not a valid argument either. Whitman et al. (2004) examined the influence of experience and specialty certification on outcomes for patients with low back pain receiving a standardized manipulation or stabilization exercise intervention program. They found that increased experience and specialty certification status did not result in an improvement in patients’ disability.
It’s also been shown that our MT techniques are not going to have any lasting positional change on tissue (Tullberg et al., 1998; Hseih et al., 1995). The MT techniques we perform are for short term and lack the necessary magnitude to provide plastic changes on the targeted tissue (Threlkeld, 1992).
Finally, joint biased technique forces are dissipated over a large area (Herzog et al., 2001; Ross et al., 2004) and are not specific to one level as we like to fool ourselves into thinking. Manipulations of the cervical spine influence the thoracic spine and vice versa.
Despite this wealth or research, I still had to ask myself why MT seems to help people in pain. If I’m not being specific to a piece of joint or tissue why do people report a reduction in pain? “We don’t treat anatomy – we treat physiology” kept ringing in my head. As it turns out, MT does have an effect after all and it’s based on a neurophysiological model. The neurophysiological model includes peripheral, spinal and/or supraspinal mechanisms (Bialosky et al., 2009).
When dealing with an injury the inflammatory response will result in the release of histamine, cytokine and prostaglandin. These chemicals can irritate nerve endings resulting in increased nociceptive input to the dorsal horn of the spinal cord and increased temporal summation. MT can lead to a significant reduction of blood and serum level cytokines (Teodorczyk-Injeyan et al., 2006) Also, soft tissue biased techniques have been shown to alter substance P levels in individuals with Fibromyalgia (Field et al., 2002). This indicates that MT could be having an effect on these chemicals at the peripheral level potentially reducing nociceptive input to the spinal cord.
MT also leads to afferent input to the dorsal horn of the spinal cord. The concept of the dorsal horn as a first site to control the modality and intensity of sensory signals conveyed to higher CNS centers dates back to Wall and Melzack’s gate control theory of pain (Melzack and Wall, 1965). Nociception from high-threshold neurons synapse in the dorsal horn and can lead to increased temporal summation. This increased temporal summation could overwhelm the normal brain response and lead to an experience of pain. We can reduce or block this temporal summation via low-threshold neurons (i.e., non-nociceptive neurons) resulting in spatial summation at the dorsal horn. By stimulating these low threshold neurons we activate glycenergic inhibitory interneurons which will spatially summate at the first synapse and prevent or at least reduce nociceptive traffic into the CNS (Foster et al., 2015).
When discussing supraspinal mechanisms and pain there is scientific evidence that structures such as the anterior cingular cortex (ACC), amygdala, periaqueductal gray (PAG), and rostral ventromedial medulla (RVM) are involved. We can indirectly influence these structures by stimulating low threshold sensory neurons during MT. These supraspinal structures can cause descending inhibition at the spinal cord level. Schmid et al. (2008) conducted a systematic review of the literature in relation to the effects of MT. They concluded that MT can assist the regulation of the top/down, bottom/up pain regulatory pathways by facilitating the inhibitory pain modulating pathways. They also advised not to increase pain significantly with MT as it can lead to promotion of inhibition of inhibitory pain modulating pathways via the above-mentioned mechanisms.
A neurophysiogical explanation of MT is scientifically plausible and should be used to explain the mechanisms of MT. This means shifting our thinking away from a strictly biomechanical model to explain the effectiveness of MT. Next time you use MT think of spatial summation and descending inhibition rather than the direction of your joint glides. After all, we don’t treat anatomy- we treat physiology.
Rob Willcott Physiotherapist
102 Main St. #15 Fredericton, NB
Bialosky JE, Bishop MD, Price DD, Robinson ME, George SZ. The mechanisms of manual therapy in the treatment of musculoskeletal pain: a comprehensive model. Man Ther. 2009 Oct;14(5):531-8.
Field T, Diego M, Cullen C, Hernandez-Reif M, Sunshine W, Douglas S. Fibromyalgia pain and substance P decrease and sleep improves after massage therapy. J.Clin.Rheumatol. 2002;8:72–76.
Foster, E., et al. (2015). Targeted Ablation, Silencing, and Activation Establish Glycinergic Dorsal Horn Neurons as Key Components of a Spinal Gate for Pain and Itch. Neuron, 85: 1289-1304
Herzog W, Kats M, Symons B. The effective forces transmitted by high-speed, low-amplitude thoracic manipulation. Spine. 2001;26:2105–2110.
Hsieh JC, Belfrage M, Stone-Elander S, Hansson P, Ingvar M. Central representation of chronic ongoing neuropathic pain studied by positron emission tomography. Pain. 1995;63:225–236.
Melzack, R., and Wall, P.D. (1965). Pain mechanisms: a new theory. Science 150, 971–979.
Ross JK, Bereznick DE, McGill SM. Determining cavitation location during lumbar and thoracic spinal manipulation: is spinal manipulation accurate and specific? Spine. 2004;29:1452–1457.
Schmid A, Brunner F, Wright A, Bachmann LM. Paradigm shift in manual therapy? Evidence for a central nervous system component in the response to passive cervical joint mobilization. Man Ther. 2008 Oct;13(5):387-96.
Seffinger MA, Najm WI, Mishra SI, Adams A, Dickerson VM, Murphy LS, Reinsch S. Reliability of spinal palpation for diagnosis of back and neck pain: a systematic review of the literature. Spine.2004;29:E413–E425.
Teodorczyk-Injeyan JA, Injeyan HS, Ruegg R. Spinal manipulative therapy reduces inflammatory cytokines but not substance P production in normal subjects. J.Manipulative Physiol Ther.2006;29:14–21.
Threlkeld AJ. The effects of manual therapy on connective tissue. Phys Ther. 1992 Dec; 72(12): 893-902.
Troyanovich SJ, Harrison DD, Harrison DE. Motion palpation: it’s time to accept the evidence.J.Manipulative Physiol Ther. 1998;21:568–571.
Tullberg T, Blomberg S, Branth B, Johnsson R. Manipulation does not alter the position of the sacroiliac joint. A roentgen stereophotogrammetric analysis. Spine. 1998;23:1124–1128.
Whitman JM, Fritz JM, Childs JD., The influence of experience and specialty certifications on clinical outcomes for patients with low back pain treated within a standardized physical therapy management program., J Orthop Sports Phys Ther. 2004 Nov;34 (11):662-72; discussion 672-5.